A cross-point memory has been known in which memory cells are arranged in intersection regions of bit lines and word lines. When an open defect of a line is detected in the cross-point memory, the open defect can be detected only by allowing a current to flow through the bit line and the word line via the memory cell. That is, it is necessary to access the memory cells in a stage in which the open defect of the bit lines is inspected.
For example, two problems to be feared are present in this inspecting method. The first problem is that when any current does not flow through the bit line and the word line, it cannot be detected where a defective portion exists in the memory cell, the word line and the bit line. The second problem is that an unnecessary stress might be applied to the memory cells in the inspection stage.
Moreover, there is disclosed a semiconductor memory which requires a process of applying a voltage to the memory cells having an insulating state to activate the memory cells, i.e., a so-called forming process (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2008-205191). In this semiconductor memory, when the forming process is also performed with respect to memory cells connected to defective lines, much time may be required for the forming process of the whole semiconductor memory.